Turbine engines, and particularly gas or combustion turbine engines, are rotary engines that extract energy from a flow of combusted gases passing through the engine in a series of compressor stages, which include pairs of rotating blades and stationary vanes, through a combustor, and then onto a multitude of turbine blades. In the compressor stages, the blades are supported by posts protruding from the rotor while the vanes are mounted to stator disks. Gas turbine engines have been used for land and nautical locomotion and power generation, but are most commonly used for aeronautical applications such as for airplanes, including helicopters. In airplanes, gas turbine engines are used for propulsion of the aircraft.
Gas turbine engines for aircraft are designed to operate at high temperatures to maximize engine thrust, so cooling of certain engine components, such as the rotor post is necessary during operation. Typically, cooling is accomplished by ducting cooler air from the high and/or low pressure compressors to the engine components which require cooling.
In adjacent compressor stages, there is a tendency for the pressure across the adjacent stages to want to back flow through a seal with the vanes, leading to additional heating of the rotor post of an upstream compressor stage, which, under the certain thermal conditions, can lead to the temperature at the upstream rotor post exceeding its creep temperature resulting unwanted creeping of the rotor post. This is especially true for the most rearward or aft compressor stage, which is subject to the greatest temperature.